The Configuration API is a large collection of endpoints revolving around three areas of Identity Cloud administration:
Applications, API clients, and settings. Applications and API clients are (for our current purposes) collections of configuration settings and values. A number of these settings and values can be managed by using the Legacy Clients and Settings API. However, the Legacy Clients and Settings API exists primarily for backwards compatibility purposes and should be avoided whenever possible. Instead, application and client management should be done using either the Configuration API or Console.
Entity types and attributes. Entity types are the databases where user profile information is stored. Attributes are (again, for our purposes) the fields that make up those databases. The Configuration API provides limited, read-only access to entity types and attributes. To actually manage these items (for example, to create an entity type or to modify a user profile attribute) use Console or the Entity and Entity Types API.
The flow. Flows are large JSON files that play a major role in determining such things as the look and feel (and the text) of your Identity Cloud registration, login, and user profile management screens and workflows. Note that you don’t interact directly with the flow: you don’t open a flow in a text editor and directly modify the JSON. Instead, flows are managed by using either the Configuration API or Console.